Diamond epitaxial films grown by plasma CVD often show
petal-like
patterns in places when observed by polarized light microscopy under
crossed polarizers. In this study, we have comprehensively characterized
shapes of the petal patterns, spatial distributions of local stress,
and microstructures of the dislocation bundle around the pattern in
CVD single crystal diamond plates, mainly using polarized optical
microscopy, Raman scattering, and high-voltage transmission electron
microscopy (HVTEM). Four-petal patterns observed in the film consisted
of a set of high-intensity petals and a set of very low-intensity
ones, which rotated with the rotation of crossed polarizers and changed
to two higher intensity petals. It was found that there was local
compressive stress around the center of the petal and local shear
stress with weak tensile stress along the four directions of [110]
equivalence. Cross-sectional Raman imaging showed that there was a
funnel-shaped compressive stress region through the center of the
petal pattern. HVTEM observations using a ∼1 μm thick
foil revealed 17 dislocations in the funnel-shaped region, corresponding
to the dislocation bundle. These dislocation types were determined
based on Burger’s vectors obtained from
gb
analysis on the TEM images under two-beam conditions.